Leaving Robert E. Lee in Richmond, Major General Stonewall Jackson traveled west to Gordonsville, an important railroad junction where the Orange and Alexandria Railroad crosses the Virginia Central. His job was to halt the advance of Major General John Pope and the newly-formed Army of Virginia. Lee placed almost half his command under Jackson in the hopes he could free the Shenandoah in preparation for the Army of Northern Virginia's advance into Maryland. Roughly 25,000 men under the command of Dick Ewell, Powell Hill and Sidney Winder rode the rail and marched west along the Virginia Central towards the Blue Ridge Mountains.

As Jackson headed west John Pope was concentrating his forces at Culpepper Court House between the Rappahannock and Rapidan Rivers. Pope hoped to follow the Orange and Alexandria to Gordonsville then move troops along the Virginia Central (the exact same route Jackson was following, only in reverse) to relieve McClellan on the Peninsula. Although Confederate and Union cavalry had clashed in a number of skirmishes and a pitched battle occurred at Orange Court House, Jackson had no idea of the size or deployment of federal forces because Nathaniel Banks was successfully screening his movements with the cavalry.

Just east of the Blue Ridge Mountains, Cedar Mountain is a twin peak rising roughly 300 feet above the fertile farmland below. Some locals call the mountain Slaughter Mountain from the name of a family that owned the land on the north end of the mountain (where the battle occurred). The North Fork of Cedar Run is big enough to be an obstacle to advancing troops, but the South Fork and other tributaries are much too small to be of any value to a commander.

On August 9, 1862, Confederates found part of Pope's Army, a corps under Nathaniel Banks north of Cedar Mountain. Jackson ordered Jubal Early to attack while Richard Ewell moved to the right in an attempt to flank the bluecoats. Confederates, under the command of Sidney Winder and A. P. Hill were also moving north along the Orange-Culpepper Road west of Cedar Mountain. Pope had ordered Banks to block Jackson to give the Army of Virginia more time to concentrate its forces. Banks, who had been Jackson's opponent in the earlier Shenandoah Valley Campaign sought to end Jackson's advance quickly with an aggressive move.

Even before the battle Jubal Early was concerned with a wide gap between his men and Ewell's. As Winder's men passed the north end of Cedar Mountain they took up positions to the Rebel left, forming something of a salient with Early's men at the center. Jackson intended to absorb the bulk of the Union attack with Early and Winder, while Ewell circled the Union flank. The problem with Jackson's plan was that Banks was expecting such an attack. An artillery duel commenced about 2:00 p.m. that afternoon.

Banks' men were in position at 2:30pm. Early reconnoitered the federal position with a brigade and sent a regiment to his right in an attempt to fill the gap between men and Ewell's men. For some reason Banks felt that Early's move was exactly the excuse he was looking for to change his orders from defensive to offensive. Unfortunately, Banks also thought he was battling an inferior force where Jackson actually outnumbered Banks almost 3-to-1.

The Union advance under Brigadier General John Geary came directly at Early, but stopped in a cornfield before a clearing waiting for support. Early thought the gap on his right was again threatened so he called for support. A. P. Hill sent his first brigade on the field, Georgians under the command of Brigadier General Edward Thomas, to fill the hole. Next, an artillery battery moved in front of Early's line, unaware of the men in the cornfield. When Geary's men saw the battery they realized cannon that close without infantry support was an easy target. As the Yankees in the cornfield rose and advanced towards the helpless battery, Early advanced and gave the Confederate artillery time to reload with canister. The effect was devastating on the Yankees, who were forced to fall back. This, the first engagement of infantry, occurred at 5:00 pm

After stopping the first Yankee advance, Early spotted more Yankees advancing on his left and sent word to Sidney Winder. Early's adjutant found a mortally wounded Winder being transported to a nearby house on the field of battle. Winder was wounded calling artillery shots, and command had fallen upon William Taliaferro (pronounced Toliver). The brigade commander was facing a test that would whiten the face of even a skilled division commander.

Brigadier General Samuel Crawford was moving towards Taliaferro's line, but his men were obscured by some trees. Nathaniel Banks accompanied them. With Union cavalry screening the far left, Banks ordered Crawford to attack the center of the Rebel line while Brigadier General George Gordon moved around the Rebel left flank. Additionally, Geary, Brigadier General Henry Prince and their commander, Major General Christopher Auger (he received his commission on the day of the battle) would again advance towards Jubal Early.

Early organized his troops and moved into an open field east of Orange-Culpepper Road as Taliaferro prepared his men, mostly west of the road. Taliaferro dispatched support (his brother Alexander's regiment) and Lt. Colonel Thomas Garnett to obliquely attack Geary's brigade, now advancing on Early. The main body of A. P. Hill's Light Division was just coming on the battlefield at 5:45 p.m when the din of battle changed from cannon to rifle, signaling the clash of infantry.

The heaviest assault came against the center and left of the Confederate line. The men Early and A. P. Hill had moved to the right were pinned down by protective Confederate fire (from Garnnett's brigade) across the front of Early's brigade, rendering them ineffective. George Gordon successfully reached the Confederate flank and Taliaferro's division quickly became disorganized where Crawford was advancing. Some of the men Crawford disrupted were the men who had been keeping Early's left from advancing. As Crawford succeeded against Garnett. Early's left flank began to move forward against Auger, Geary and Prince.

Watching from his post, Stonewall Jackson rode up to Taliaferro's division on the west side of Culpepper Road. With sword drawn Old Jack cried "Rally men, Jackson will lead you. Follow me!" At that time Taliaferro rode up and insisted Jackson return to his command post but Jackson's effort worked as the line firmed. Less than 15 minutes had passed.

Jackson, however, did not return to his command post. Instead, he went south on the Orange-Culpepper Road in search of A. P. Hill. The first brigade he came upon was Lawrence Branch's North Carolinians. Jackson ordered them forward to support Taliaferro's endangered left flank. As Branch's men reached their position an ill-advised Union attack by George Gordon had just gotten underway. With the help of the North Carolinians, the attack was repulsed.

Slowly, the Confederates had been gaining the offensive. Now, with the entire line firm and the federals withdrawing to their original lines, Jackson decided to use it to his advantage by pressing the Yankees. A. P. Hill pushed the Yankees back to Culpepper. Slowly and methodically, Hill advanced, driving Banks back under the light of an almost full moon. Then Grumble Jones arrived with news that a second Union corps had entered the battlefield. With that, Hill withdrew. The following night Jackson withdrew back across the Rapidan.

The Battle of Cedar Mountain introduced John Pope to the way war was waged under Lee and Jackson, and served to set-up Pope for his defeat three weeks later at Second Bull Run. Before the Battle of Cedar Mountain Pope seemed decisive and bold on the field and in communications. After Nathaniel Banks' defeat Pope seemed worried about maintaining lines of supply and more importantly, a line of retreat.